Gas barrier coating compositions containing platelet-type fillers

ABSTRACT

Disclosed is a gas barrier coating and multilayer packaging materials made therefrom. The gas barrier coating includes a polyamine (A), a polyepoxide (B), and a filler (C). Polyamine (A) includes at least one of the following: (a) an initial polyamine, and (b) an ungelled polyamine adduct which is the reaction product of the initial polyamine and epichlorohydrin and/or a polyepoxide having a plurality of glycidyl groups linked to an aromatic member. Polyepoxide (B) includes a polyepoxide having a plurality of glycidyl groups linked to an aromatic member. Filler (C) includes a platelet-type filler with the following particle size distribution: (a) a number mean particle diameter in the range from about 5.5 to about 15 microns, and (b) a volume mean particle diameter in the range from about 8 to about 25 microns. In addition, the present invention provides glossy, multilayer packaging materials containing an oxygen barrier material layer having an oxygen permeability constant not more than 0.05 in cubic centimeter-mil/100 square inches/atmosphere/day at 30° C. and 50% R.H. The glossy, multilayer packaging material includes: (a) at least one layer of a substrate material, and (b) at least one layer of the gas barrier material described above.

BACKGROUND OF THE INVENTION

The technical field of the present invention relates to gas barriercoating compositions and multilayer packaging materials made therewith.

Plastics have found increasing use as replacements for glass and metalcontainers in packaging. Advantages of such plastic packaging over glasspackaging include lighter weight, decreased breakage and potentiallylower costs. Moreover, an advantage of plastic packaging over metalpackaging is that the former can more easily be designed as re-closable.Notwithstanding the above, shortcomings in the gas-barrier properties ofcommon plastic packaging materials (e.g., polyesters, polyolefins andpolycarbonates) present major problems to those in the packagingindustry when used to package oxygen-sensitive items and/or carbonatedbeverages.

Specifically, gases such as oxygen and carbon dioxide can readilypermeate through most of the plastic materials commonly used by thepackaging industry. The oxygen permeability constant (herein referred toas "OPC") of such plastic materials, which quantifies the amount ofoxygen which can pass through a film or coating under a specific set ofcircumstances, is generally expressed in units of cubiccentimeter-mil/100 square inches /atmosphere/day. This is a standardunit of permeation measured as cubic centimeters of oxygen permeatingthrough 1 mil (25.4 micron) thickness of a sample, 100 square inches(645 square centimeters) in area, over a 24-hour period, under a partialpressure differential of one atmosphere at specific temperature andrelative humidity (R.H.) conditions. As used herein, OPC values arereported at 30° C. and 50% R.H. unless otherwise stated.

Since many foods, beverages, chemicals, medicines, medical supplies andthe like are sensitive to oxidation, they typically must be protectedfrom the ingress of oxygen into the sealed container so as to preventthe discoloration and/or spoilage of the item contained therein.Moreover, carbonated beverages should be stored in sealed containerswhich prevent the egress of carbon dioxide therefrom so as to keep thebeverage from going flat. As used herein, the term "flat" refers to acarbonated beverage losing at least about 10% of its carbonation,typically at least about 15% of its carbonation, and more typically atleast about 20% of its carbonation. Accordingly, since oxygen and carbondioxide can readily permeate through most plastic materials used by thepackaging industry, the shelf-life of items stored in conventionalplastic containers is reduced when compared to their shelf-life whenstored in glass or metal containers.

Some examples of oxygen sensitive items whose shelf life would begreatly reduced if stored in conventional plastic containers areperishable foods and beverages such as tomato-based products (e.g.,ketchup, tomato sauces and tomato pastes), juices (e.g., fruit andvegetable juices) and malt beverages (e.g., beer, ale, malt liquor). Inthese instances, exposure to minute amounts of oxygen over a relativelyshort period of time adversely affects their taste. Some examples ofcarbonated beverages whose shelf life would be greatly reduced if storedin conventional plastic containers are soft drinks, malt beverages,sparkling water, sparkling wines, champagne, and the like.

One of the common packing materials used today in the food and beverageindustry is poly(ethylene teraphthalate) ("PET"). Notwithstanding itswidespread use, PET has a relatively high OPC value (i.e., 6.0). Assuch, although it has been used for making many types of food andbeverage containers, the food and beverage industry has sought ways toimprove the OPC value of such packaging materials. It should be notedthat, typically, oxygen permeates through a film and/or coating morereadily than does carbon dioxide. Accordingly, although OPC valuespertain to the permeability of oxygen through a film and/or coating,lowering a coating's OPC value not only improves its oxygen barrierproperties, but also improves its carbon dioxide barrier properties.

One of the methods disclosed in the literature as a means of improving aplastic packaging material's OPC value pertains to chemically and/orphysically modifying the plastic. This method is typically expensive andcan create recycleability problems. Another method disclosed in theliterature as a means of improving a plastic packaging material's OPCvalue pertains to coating the plastic material with a gas barriermaterial (e.g., a gas barrier coating composition or a gas-barrierfilm). This method is typically less expensive than the method set outabove and creates fewer, if any, recycleability problems.

Numerous gas barrier coating compositions have been disclosed in theprior art. For example, polyepoxide-polyamine based gas barrier coatingcompositions having very low OPC values are the subject ofcommonly-owned U.S. Pat. Nos. 5,006,381; 5,008,137 and 5,300,541 and WO95/26997. These coatings have found commercial acceptance as barriercoatings for polymeric containers. However, further improvements arestill desirable by certain segments in the packaging industry. Anexample of such desired improvements would include the development ofgas barrier coatings which have OPC values of not more than 0.05 and asmooth and glossy appearance.

One specific approach which has been disclosed as a means for improvingthe gas barrier properties of resin-based coating compositions, ingeneral, is to incorporate therein the use of platelet shaped inorganicfillers (hereinafter referred to as "platelet-type" fillers). Withoutbeing bound to theory, it is believed that such blends of platelet-typefillers and resins function, at least in part, by forming tortuous pathsfor diffusion of permeating gases there through.

There are a number of examples in the patent literature on the use ofinorganic platelet-type fillers to improve the gas barrier properties ofcoating compositions. For example, WO 95/26997 states that the use ofpigments in the polyepoxide-polyamine based gas barrier coatingcompositions disclosed therein may further reduce the gas permeabilityof the resultant barrier material. Examples of preferred pigments listedtherein include micas, aluminum flakes and glass flakes due to theirplatelet-type structure. There is, however, no disclosure therein as towhich platelet-type particles, if any, can be used in order to produce agas barrier coating having not only an OPC value of not more than 0.05,but also a smooth and glossy appearance.

U.S. Pat. Nos. 4,528,235 and 1,018,528 disclose thin polymer filmscontaining small sized platelet-type fillers. The preferred polymer ispolycaprolactam or high density polyethylene. According to thosepatents, there is from 10 to 50 percent of a platelet-type fillerpresent therein which has an average equivalent diameter of from 1 to 8micrometers, a maximum equivalent diameter of about 25 micrometers, andan average thickness of less than 0.5 micrometers. The preferred filleris talc. Ground mica, platelet silicas, flaked metal and flaked glassare also disclosed as being suitable fillers.

In some instances, the use of platelet-type fillers in coatingcompositions significantly improves the coatings' gas barrierproperties. However, in other instances, the use of platelet-typefillers has little, if any, effect on the coating's gas barrierproperties and/or reduces the resulting coating's gloss and smoothness.In the packaging industry, while it is often desirable for a coating tohave excellent gas barrier properties, it is also often equallydesirable for the coating to have a smooth and glossy appearance.

Therefore, when the use of platelet-type fillers improves a coating'sgas barrier properties, the resulting OPC values are oftentimes eitherstill too high to be used when making plastic packaging materials forfoods, beverages, chemicals, medicines, medical supplies and the likewhich are highly sensitive to oxidation, or too rough and dull tosatisfy appearance requirements. Accordingly, notwithstanding the manyadvantages associated with the polymeric packaging materials, some itemsare still stored in glass or metal containers due to the gaspermeability problems of polymeric packaging materials.

The extensive prior art in this area shows the unfilled need for aspecific combination of a filler and a gas barrier coating which wouldhave a very low OPC value (i.e., an OPC value of not more than 0.05) anda smooth and glossy appearance.

SUMMARY OF THE INVENTION

The present invention provides a gas barrier coating composition whichincludes: a polyamine (A), a polyepoxide (B), and a filler (C).Polyamine (A) includes at least one of the following: (a) an initialpolyamine, or (b) an ungelled polyamine adduct. Polyepoxide (B) includesa polyepoxide having a plurality of glycidyl groups linked to anaromatic member. Filler (C) is characterized as a platelet-type fillerwith the following particle size distribution: (a) a number meanparticle diameter ranging from about 5.5 to about 15 microns, and (b) avolume mean particle diameter ranging from about 8 to about 25 microns.When cured, the gas barrier coatings of this invention have an OPC valueof not more than 0.05, and a 20° gloss of at least 60% reflected light.

The present invention also provides smooth and glossy, multilayerpackaging materials which include: (a) at least one layer of a substratematerial, and (b) at least one layer of the gas barrier materialdescribed above.

DETAILED DESCRIPTION OF THE INVENTION

As used herein, the term "glossy" refers to a cured coating having agloss, as measured at an angle of 20° using a Gardner Glossgard IIa 20°Glossmeter from Gardner Instruments, of at least 60% reflected light.

As used herein, the term "ungelled polyamine adduct" refers to anamine-functional polymeric resin which is soluble and/or dispersible ina liquid medium.

As used herein, the term "number mean particle diameter" refers to thesum of the equivalent circle diameter of all the particles in the samplethat were analyzed (Σd) divided by the total number of the particlesthat were analyzed.

As used herein, the term "equivalent circle diameter" refers to thediameter of a circle having a projected area equal to the projected areaof the particle in the sample being analyzed.

As used herein, the term "volume mean particle diameter" refers to thecube root of the sum of the cube of the equivalent spherical diameter ofall the particles in the sample that were analyzed ((Σd³)^(1/3)) dividedby the total number of the particles that were analyzed.

As used herein, the term "equivalent spherical diameter" refers to thediameter of a sphere having a volume equal to the volume of the particlebeing analyzed.

All particle size measurements pertaining to the filler used whenpracticing this invention are as determined by a HORIBA LA-900 laserscattering particle size distribution analyzer from Horiba Instruments,Inc. in Irving, Calif. The HORIBA LA-900 works off the same principle asmany conventional laser scattering particle size distribution analyzers.

For example, light traveling in a homogeneous medium travels in straightlines. However, when light travels through a medium containing particlesof a material, the particles cause the light to scatter. For a singleparticle, the amount of scattering in a particular direction dependsupon the size, shape, and composition of the particle and the wavelengthof the incident light. For a collection of particles, light scatteredfrom all of the particles contributes to the total intensity of lightscattered in a particular direction relative to the incident light. Bymeasuring the amount and/or intensity of light scattered throughout anumber of angles relative to the incident light, it is possible to inferproperties of the particles that induce the scattering. In particular,for particles of small size and similar composition, the pattern ofscattered light is indicative of the sizes of the scattering particles.

Many conventional analyzers have used the aforementioned technique ofanalyzing the scattered light intensity to determine the spectrum ofparticle sizes for a mixture of small particles of varying sizes.Particle size analyzers using this technique typically sample theangular distribution of the intensity of the light scattered from themixture, process the data, and produce numerical values and possibly agraph or a histogram as output. The analyzer output represents thenumber or volume fraction of scattering particles in the mixture as afunction of the size of the particles and is usually called a particlesize distribution.

For classical light scattering analysis, the problem of relating theangular distribution of scattered light to the size of the scatteringparticle has been solved mathematically for the case of a sphericalparticle illuminated by a beam of unpolarized light. The mathematicalsolution is given by a theory proposed by Gustav Mie. The Mie theory isset forth in Chapter 4 of the book, Absorption and Scattering of Lightby Small Particles, by Craig F. Bohren and Donald R. Huffman (John Wiley& Sons, 1983). Some particle size analyzers employ the Mie theory todetermine particle size distributions from the observed pattern ofscattered light.

Although such analyzers are not limited to the analysis of only samplescontaining particles of spherical shape, the particle sizes are reportedas radii of spheres that are equivalent to the actual particles in termsof light scattering. For most applications, the equivalent-spherespecification of a particle size distribution is sufficient tocharacterize the actual particle size distribution. Mathematical modelshave also been derived for particular particle shapes other thanspherical, but they have been found to have limited value since, forscattering, only the average behavior of a large number of particles isof interest.

Since scattering is also a function of the wavelength of the incidentlight, some analyzers use incident light of a single wavelength. Forthis purpose, a laser has been the typical light source. Lasers havebeen used which produce light in the visible and near-visible wavelengthrange.

In many typical particle size distribution analyzers, a source ofunpolarized light is projected in a beam to impinge upon a sample. Thesample contains the particles whose sizes are under investigation. Theparticles are dispersed in the region of the sample that is illuminatedby the incident light beam. The particles scatter light in patterns thatare dependent on the ratio of the size of the particle to the wavelengthof the light, and on the refractive index of the particle material. Therefractive index, a complex function of wavelength, is a measure of howmuch the light is refracted, reflected, and absorbed by the material.For a beam of unpolarized light incident on a random mixture of smallparticles, the scattering pattern is symmetric about the axis of theincident beam. The scattering is the result of the refraction,reflection, and absorption by the particles, as well as diffraction ateach particle surface where a light ray in the incident beam is tangentto the particle surface.

Light that scatters at a particular angle with respect to the incidentbeam may be rotated about the beam axis without changing the scatteringangle. A large number of rays scattering from a single particle at agiven scattering angle will fill all rotational orientations and thusform a cone of light, with the apex at the scattering particle and withthe generating angle (one-half the apex angle) of the cone equal to thescattering angle. The pattern of light rays scattering at all anglesfrom a single particle may thus be thought of as made up of a continuousseries of open cones of light, with the generating angle for a givencone corresponding to the scattering angle for the light comprising thesurface of that cone. The axes of all of the cones are collinear withthe line defined by the incident beam, and the apexes of the cones arelocated at the scattering particle. At a distance from the scatteringparticle, a plane perpendicular to the incident beam will intersect agiven cone in a circle. Planes not perpendicular to the incident beamwill intersect a given cone in a curved line comprising a conic section(i.e., an ellipse, a parabola, or a hyperbola), depending upon theorientation of the plane. Regardless of form, the curved line ofintersection represents a single scattering angle.

In particle size analyzers, it is not necessary to measure thescattering angle with infinite precision. Nevertheless, better angularresolution in the analyzer provides better particle size resolution. Inorder to address angular precision effects directly, the set of allscattering angles falling between a precise lower angular limit and aprecise upper angular limit will be referred to as an "angle class" ofsome intermediate angle. Light scattered within an angle class scattersinto the region between two cones of slightly different size. Thesmaller (inner) of the two cones is generated by the lower angular limitof the angle class and the larger (outer) cone is generated by the upperangular limit. The apexes of both cones are located at the scatteringparticle.

The inner and outer cones of an angle class define a circular annularregion on a plane perpendicular to the incident beam and a more complexshaped region (corresponding to a conic section) on a plane notperpendicular to the incident beam. Scattered light rays intersectingthe interior of such a region are rays which have scattered through anangle between the two generating angles of the cones. Thus any light rayintersecting such a region belongs to the angle class defined by thatregion. Some conventional analyzers employ ring-shaped light detectorsto measure the amount of light that scatters in an angle classdetermined by the radius and width of the ring and its distance from thescattering region. To correlate correctly the detected light with ascattering angle, these ring-shaped detectors are typically mounted andaligned precisely perpendicular to the incident beam.

Since the interaction region of the incident beam with the particlesgenerally has a finite extent, multiple particles at different locationsin the incident beam will each contribute multiple overlapping cones ofscattered light, with the apexes of the cones offset by the distancebetween the particles. Particles of the same size will have overlappingscattered-light cones of similar intensity variations, whereas particlesof different sizes will have overlapping scattered-light cones ofdifferent intensity variations.

When the light beam illuminates a sample volume of finite extent, aconverging lens may be used to direct parallel rays of light, each bydefinition scattered through the same scattering angle (by differentparticles), to a single point on a light detector in the focal plane ofthe lens. A lens that functions in this manner performs a Fouriertransform, so that all light arriving at a given point on the detectoris known to have been scattered by the sample through a particularscattering angle, regardless of the location of the scattering particlein the sample volume.

The effect of the converging lens is to transform the spatialdistribution of the scattered light it receives to that of an equivalentvirtual system in which the light distribution in the focal plane of thelens is the same as if all the scattering particles were located at apoint coincident with the optic center of the lens. The light detectorsare placed in the focal plane of the lens. The line from the opticcenter of the lens to the focal point of the lens is usually called theoptic axis.

If a scattered ray passes through different refracting media, such asair and a sample suspension fluid, before detection, then an appropriatecorrection is typically applied to the ray's apparent angle of scatterto determine its true angle of scatter. Use of a lens and recognition ofthe virtual scattering system simplifies the correction.

The intensity of light scattered as a function of scattering angle, whenexperimentally determined as above for a sample composed of manyparticles of a range of different sizes, consists of the summation ofthe scattered light from all the particles. If it is assumed that eachsize particle in the sample scatters light according to a givenmathematical theory and in proportion the relative number of such sizeparticles present, then it is mathematically possible to determine fromthe experimental data the relative numbers of each size particleconstituting the sample (i.e., to determine the size distribution of thesample. The well-known mathematical process by which the sizedistribution may extracted from the composite data is called aninversion process, or sometimes a deconvolution process.

In the usual convention, a scattering angle of zero degrees coincideswith unscattered light, and a scattering angle of 180 degrees representslight reflecting directly back into the incident beam. Scattering anglesbetween 90 and 180 degrees are termed back scattering.

Similar to these conventional particle size distribution analyzers, theHORIBA LA-900 works by irradiating particles dispersed in a solutionwith a red light beam and a blue light beam which is obtained byfiltering a tungsten lamp in parallel with an He-Ne laser. The particlescause the light to scatter at various angles. A condenser lens is usedwith an array detector at the focal point of the lens. There are alsodetectors positioned in the front, side and rear of the sample. From theangular measurement of the scattered light by all the detectors, theparticle size distribution of the sample is calculated. Thesecomputations are made by the particle size distribution analyzer byusing the Mie scattering light theory. Using the technique set outabove, the HORIBA LA-900 laser scattering particle size distributionanalyzer can provide an accurate, reproducible assessment of particlesizes in the range from 0.04 microns to 1,000 microns.

To measure particles having a diameter less than 0.1 microns, the HORIBALA-900 uses three separate detectors--one for the front, side and rearscattering. As the light source for detecting scattering on the side andrear, the HORIBA LA-900 uses a tungsten lamp. In the HORIBA LA-900, thesmall angle forward scattered light is conventionally given by an He-Nelaser and detected by the ring detector and the large angle and rearscattered light is given by the tungsten lamp and detected by aphotodiode. For a complete description of how the HORIBA LA-900 works,see U.S. Pat. No. 5,4278,443.

The gas barrier coating compositions of the present invention include: apolyamine (A), a polyepoxide (B), and a filler (C). Polyamine (A) can bean initial polyamine, an ungelled polyamine adduct, or a mixturethereof.

The initial polyamine used as, or in the making of, polyamine (A) istypically characterized as having a substantial aromatic content.Specifically, at least 50 percent of the carbon atoms in the initialpolyamine are in aromatic rings (e.g., phenylene groups and/ornaphthylene groups). Preferably the number of the initial polyaminecarbon atoms in aromatic rings is at least 60 percent, more preferablyat least 70 percent, and even more preferably at least 80 percent. Thisinitial polyamine can be represented by the structure:

    Φ-(R.sup.1 NH.sub.2).sub.k

where:

k is 1.5 or greater,

Φ is an aromatic-containing organic compound, and

R¹ is an allyl group having between 1 and 4 carbon atoms.

Preferably, k is 1.7 or greater, more preferably 1.9 or greater, andeven more preferably, 2.0 or greater. Preferably, R¹ is not larger thanC₃, more preferably not larger than C₂, and even more preferably notlarger than C₁. Typically, Φ comprises an aryl group, preferably abenzyl and/or a naphthyl group.

The gas barrier coating compositions of the present invention can beproduced without having to form an ungelled polyamine adduct. Ininstances where a polyamine adduct is not formed, all of the epoxiderequired for curing the gas barrier coating composition (i.e.,polyepoxide (B)) is blended with the initial polyamine (i.e., polyamine(A)).

When an initial polyamine is pre-reacted to form an adduct, sufficientactive amine hydrogen groups must be left unreacted so as to providereaction sites for reacting during the final curing step. Typically,about 10 to about 80 percent of the active amine hydrogens of thepolyamine are reacted with epoxy groups. Pre-reacting fewer of theactive amine hydrogens reduces the effectiveness of the pre-reactionstep and provides little of the linearity in the polymer product that isone of the advantages of forming the adduct.

In accordance with one embodiment, a polyamine adduct is formed byreacting the initial polyamine with epichlorohydrin. By carrying out thereaction at polyamine to epichlorohydrin molar ratios greater than about1:1 in the presence of an alkali, a primary reaction product ispolyamine groups joined by 2-hydroxypropylene linkages. The reaction ofm-xylylenediamine ("MXDA"), a preferred polyamine, with epichlorohydrinis described in U.S. Pat. No. 4,605,765, and such products arecommercially available as GASKAMINE 328® and GASKAMINE® 328S fromMitsubishi Gas Chemical Company.

In accordance with another embodiment, a polyamine adduct is formed byreacting the initial polyamine with polyepoxides in which a plurality ofglycidyl groups are linked to an aromatic member. As used herein, theterm "linked" refers to the presence of an intermediate linking group.Such polyepoxides can be represented by Formula (I): ##STR1## where: R²is phenylene or naphthylene;

X is N, NR³, CH₂ N, CH₂ NR³, O, and/or C(O)--O, where R³ is an alkylgroup containing 1 to 4 carbon atoms, a cyanoethyl group or cyanopropylgroup;

n is 1 or 2; and

m is 2 to 4.

Examples of such polyepoxides include: N,N,N',N'-tetrakis(oxiranylmethyl)-1,3-benzene dimethanamine (e.g., that which iscommercially available as TETRAD X epoxy resin from Mitsubishi GasChemical Co.), resorcinol diglycidyl ether (e.g., that which iscommercially available as HELOXY® 69 epoxy resin from Shell ChemicalCo.), diglycidyl esters of phthalic acid (e.g., that which iscommercially available as EPI-REZ® A-100 epoxy resin from Shell ChemicalCo.), and triglycidyl para-aminophenol (e.g., that which is commerciallyavailable as Epoxy Resin 0500 from Ciba-Geigy Corporation).

Optionally, if a polyamine adduct is formed, it may also include up toabout 20 weight percent a novolac epoxy resin or a bisphenol F epoxyresin. This percentage is based upon the total resin solids of theadduct.

Notably excluded from the types of epoxides that can be reacted with theinitial polyamine to form a polyamine adduct are bisphenol A type epoxyresins. Alternatives for such bisphenol A type epoxides which can bereacted with the initial polyamine in accordance with the presentinvention include novolacs with higher glycidyl functionality (e.g.,those commercially available from Dow Chemical Co. as DEN-438 and/orDEN-439).

The reaction of the epoxide and the initial polyamine to produce theungelled adduct is carried out at temperatures and concentrations ofreactants sufficient to produce the desired ungelled product. Thesetemperatures and concentrations will vary depending upon the selectionof starting materials. Typically, however, reaction temperatures willrange from about 40° C. to about 140° C., with lower temperatures (e.g.,from about 40° C. to about 110° C.) being preferred for those systemsthat are more susceptible to gellation. Similarly, concentrations ofreactants will typically range from about 5 to about 100 percent byweight of reactant in an appropriate solvent depending upon theparticular molar ratio and type of reactants. Lower concentrations ofreactants are generally preferred for those systems that are moresusceptible to gellation.

Specific reaction conditions can readily be chosen by one skilled in theart guided by the disclosure and the examples herein. Moreover,preparation of an ungelled amine-functional polymeric adduct is alsodescribed in commonly-owned U.S. Pat. No. 5,006,381, columns 2 through7. The description in U.S. Pat. No. 5,006,381, of the preparation ofsuch amine-functional polymeric adducts, is incorporated herein byreference.

In most instances, when compared to the non adduct producing approach,forming the polyamine adduct has the advantage of increasing molecularweight while maintaining linearity of the resin, thereby avoidinggellation. This can be achieved by using an initial polyamine having nomore than two primary amino groups.

Typically, the initial polyamines react relatively slowly withpolyepoxide (B). On the other hand, the aforementioned polyamine adductreacts relatively quickly with polyepoxide (B). Accordingly, anotheradvantage of forming the polyamine adduct is that the reaction periodnecessary to form the resulting gas barrier coating is significantlyreduced.

Polyepoxide (B) used when practicing this invention may be any epoxideknown to those of skill in the art which can react with polyamine (A) toform gas barrier coating compositions. Preferably, polyepoxide (B)includes those polyepoxides in which a plurality of glycidyl groups arelinked to an aromatic member are represented by Formula (I) describedearlier. Specific examples of such a group of polyepoxides are also thesame as those described earlier which can be reacted with the initialpolyamine to form the ungelled polyamine adduct.

When polyepoxides are employed in both the formation of a polyamineadduct, they may be the same or different as those used as polyepoxide(B). Typically, if a polyamine adduct is used in the formation of thegas barrier coatings of this invention, the epoxides used in forming thepolyamine adduct and those used as polyepoxide (B) have epoxyfunctionality of at least about 1.4, and preferably at least about 2.0The presence of small amounts of monoepoxides may not, however, beobjectionable.

Polyepoxide (B) may include polyepoxides that are saturated orunsaturated, aliphatic, cycloaliphatic, aromatic, or heterocyclic, andmay be substituted with non-interfering substituents such as hydroxylgroups or the like. Generally, such polyepoxides may includepolyglycidyl ethers of aromatic polyols, which may be formed byetherification of aromatic polyols with epichlorohydrin ordichlorohydrin in the presence of an alkali. Specific examples of suchinclude: bis(2-hydroxynaphthyl)methane, 4,4'-dihydroxylbenzophenone,1,5-dihydroxy-naphthalene and the like. Also included in the category ofa suitable polyepoxide (B) are polyglycidyl ethers of polyhydricaliphatic alcohols including cyclic and polycyclic alcohols.

The epoxy group equivalent weight of polyepoxide (B) is preferablyminimized so as to avoid unnecessarily introducing molecular groups intothe cured polymeric network that are not the preferred groups of thisinvention. Generally, polyepoxide (B) has a molecular weight above about80. Preferably, the molecular weight of polyepoxide (B) is in the rangefrom about 100 to about 1,000, and more preferably from about 200 toabout 800. Moreover, polyepoxide (B) generally has an epoxy equivalentweight above about 40. Preferably, the equivalent weight of polyepoxide(B) is in the range from about 60 to about 400, and more preferably fromabout 80 to about 300.

The diglycidyl ethers of an aromatic polyol such as bisphenol A or analiphatic alcohol such as 1,4-butanediol are not preferred whenpracticing the present invention. However, they may be tolerated whenused to cure preferred embodiments of the polyamine adduct. Diglycidylethers of bisphenol F are preferred over bisphenol A based epoxides forthe sake of low oxygen permeability. It is theorized that the presenceof methyl groups in bisphenol A has a detrimental effect on oxygenbarrier properties. Thus, isopropylidene groups are preferably avoided.Other unsubstituted alkyl groups are believed to have a similar effect,and constituents containing such groups are preferably avoided in thepresent invention.

In addition to polyamine (A) and polyepoxide (B), the gas barriercoating compositions of this invention further include filler (C). Ithas been discovered that, in order for the presence of filler (C) tolower the OPC value of the gas barrier coating composition disclosedherein to not more than 0.05, and to maintain a smooth appearance havinga 20° gloss of at least 60% reflected light, filler (C) is characterizedas a platelet-type filler having the following particle sizedistribution: (a) a number mean particle diameter ranging from about 5.5to about 15 microns, and (b) a volume mean particle diameter rangingfrom about 8 to about 25 microns. Preferably, the platelet-type fillerincluded in filler (C) has the following particle size distribution: (a)a number mean particle diameter ranging from about 7.5 to about 14microns, and (b) a volume mean particle diameter ranging from about 10to about 23 microns; and more preferably the following particle sizedistribution: (a) a number mean particle diameter ranging from about 9.5to about 13 microns, and (b) a volume mean particle diameter rangingfrom about 14 to about 20 microns. In addition to the above, inpreferred embodiments of this invention, the platelet-type fillerincluded in filler (C) further has the following particle sizedistribution: (a) at least about 55 percent by number of its particleshaving a diameter greater than 7 microns, and (b) less than about 15percent by number of its particles having a diameter greater than 30microns; preferably: (a) at least about 75 percent by number of itsparticles having a diameter greater than 7 microns, and (b) less thanabout 10 percent by number of its particles having a diameter greaterthan 30 microns; and more preferably: (a) at least about 95 percent bynumber of its particles having a diameter greater than 7 microns, and(b) less than about 5 percent by number of its particles having adiameter greater than 30 microns.

It has been observed that the incorporation of a sufficient amount of aplatelet-type filler having a particle size distribution within theseparameters into a barrier coating comprising polyamine (A) andpolyepoxide (B) as described herein results in a gas barrier coatingcomposition which, when cured, has an OPC value of not more than 0.05and a 20° gloss of at least 60% reflected light. However, it has alsobeen observed that, when a platelet-type filler is used which has aparticle size distribution outside of the aforementioned parameters, orif an insufficient amount of a platelet-type filler is used which has aparticle size distribution within the aforementioned parameters, theresulting gas barrier coating may not have an OPC value of not more than0.05 and/or a 20° gloss of at least 60% reflected light.

When filler (C) has the following particle size distribution: (a) anumber mean particle diameter ranging from about 9.5 to about 15microns, and (b) a volume mean particle diameter ranging from about 14to about 25 microns, in order for the resulting gas barrier coating tohave an OPC value of not more than 0.05 and a 20° gloss of at least 60%reflected light, filler (C) is preferably present in an amount rangingfrom about 5 to about 50 weight percent, more preferably in an amountranging from about 6 to about 45 weight percent, and even morepreferably from about 7 to about 40 weight percent. These weightpercentages are based upon the total solids weight of the gas barriercoating composition.

However, when the number mean particle diameter of filler (C) rangesfrom about 5.5 to less than 9.5 microns, and/or when the volume meanparticle diameter ranges from about 8 to less than 14 microns, in orderfor the resulting coating composition to have an OPC value of not morethan 0.05, filler (C) is preferably present in an amount ranging fromabout 12 to about 50 weight percent, more preferably in an amountranging from about 15 to about 45 weight percent, and even morepreferably from about 18 to about 40 weight percent. These weightpercentages are based upon the total solids weight of the gas barriercoating composition.

Any suitable platelet-type filler which has the aforementioned particlesize distribution and which is compatible with the barrier coatingcomposition described above can be used when practicing this invention.Examples of such suitable fillers include: mica, vermiculite, clay,talc, micaeous iron oxide, silica, flaked metals, flaked graphite,flaked glass, flaked phthalocyanine, and the like. The preferred fillerfor the purposes of this invention is mica due to its commercialavailability.

Micas which can be used when practicing this invention include naturalmicas and synthetic micas. Examples of natural micas include: muscovite(K₂ Al₄ (Al₂ Si₆ O₂₀)(OH)₄), phlogopite (K₂ (Mg,Fe²⁺)₆ (Al₂ Si₆O₂₀)(OH,F)₄), and biotite (K₂ (Fe²,Mg)₆ (Al₂ Si₆ O₂₀)(OH)₄). Examples ofsynthetic micas include: fluorophlogopite (K₂ Mg₆ Al₂ Si₆ O₂₀ F₄) andbarium disilicic (Ba₂ Mg₆ Al₂ Si₆ O₂₀ F₄). Of the micas which have theaforementioned particle size distribution, the preferred, for thepurposes of this invention, is muscovite mica due to its commercialavailability.

The polymers that comprise the chief film-forming resin of the gasbarrier coating composition of the present invention are cured in situwhen polyamine (A) and polyepoxide (B) are mixed together. Each aminehydrogen of polyamine (A) is theoretically able to react with one epoxygroup and is considered as one amine equivalent. Thus, a primary aminenitrogen is considered as difunctional in the reaction with epoxides toform the gas barrier material.

For the purposes of this invention, these two components are typicallyreacted in a ratio of the equivalents of active amine hydrogens inpolyamine (A) to equivalent of epoxy group in polyepoxide (B) of atleast about 1:1.5. In order to produce a gas barrier material which isstrong, flexible, moisture resistant and solvent resistant, the ratio ofthe equivalents of active amine hydrogens in polyamine (A) to equivalentof epoxy group in polyepoxide (B) is preferably in the range from about1:1.5 to about 1:3.0, more preferably from about 1:1.7 to about 1:2.8,and even more preferably from about 1:2.0 to about 1:2.5.

Preferably, the cured reaction product of polyamine (A) and polyepoxide(B) contains a substantial number of unreacted amine hydrogens. However,although maximizing the amount of polyamine reactant is generallydesirable for the sake of maximizing gas barrier properties,insufficient numbers of epoxy groups may not provide enough crosslinkingto yield a film which is strong, moisture resistant and solventresistant. On the other hand, the use of more epoxy than the preferredamounts may provide excessive crosslinking to yield a film that is verybrittle.

As the amount of amine nitrogen in the gas barrier coating increases,the coating's OPC value decreases. When practicing this invention, theamine nitrogen content in the cured gas barrier coating is typically atleast about 6.0 weight percent. Preferably, the cured gas barriercoatings of this invention have an amine nitrogen content of at leastabout 6.5 weight percent, and more preferably of at least about 7.0weight percent. Typically, for economical reasons, the maximum amount ofamine nitrogen content in the cured gas barrier coating of thisinvention is generally less than about 20 weight percent, more typicallyless than about 17 weight percent, and even more preferably less thanabout 15 weight percent. These weight percentages are based upon totalresin solids weight of the gas barrier coating.

Cured films of the gas barrier coating compositions prepared inaccordance with the present invention have a molecular network thatconsists predominantly of two molecular groups:

(1) aminoalkyl substituted aromatic groups of the type

    <NR.sup.4 ΦR.sup.4 N<

where, R⁴ is an alkyl group containing not more than 4 carbons,preferably not more than 3, more preferably not more than 2, and evenmore preferably not more than 1 carbon atom), and

(2) --CH₂ CH(OH)CH₂ -- (2-hydroxypropylene groups) groups.

Typically, the amount of the aminoalkyl substituted aromatic groupspresent in the cured gas barrier coating is at least about 50 weightpercent, more preferably at least about 55 weight percent, and even morepreferably at least about 60 weight percent. The amount of the2-hydroxy-propylene groups present in the cured gas barrier coating istypically at least about 20 weight percent, more preferably at leastabout 30 weight percent, and even more preferably at least about 40weight percent. These weight percentages are based upon the total weightof resin solids of the gas barrier coating. Examples of theseembodiments include m-xylylenediamine adducted with epichlorohydrin orwith N,N,N',N' tetrakis (oxiranylmethyl)-1,3-benzene dimethanamine(TETRAD X epoxy resin) and cured with TETRAD X epoxy resin.

It has been discovered that excellent gas barrier properties can beattained when the cured film network of the gas barrier coating containsat least about 70 weight percent of aminoalkyl substituted aromaticgroups and/or 2-hydroxypropane groups. For the purposes of thisinvention, the gas barrier coating preferably contains at least about 80weight percent of these two molecular groups, more preferably at leastabout 90 weight percent, and even more preferably at least about 95weight percent. These weight percentages are based upon the total weightof resin solids of the gas barrier coating.

As stated above, in one preferred embodiment, at least 50 percent of thecarbon atoms in the initial polyamine used as, or in the making of,polyamine (A) are in an aromatic ring(s). In a particularly usefulembodiment, R⁴ in the >NR⁴ ΦR⁴ N< group contains a single carbon atom.Accordingly, when Φ is benzene, at least seventy percent of the carbonatoms are in aromatic rings.

It should be understood, however, that excellent gas barrier propertiesmay still be attained without the optimum levels of the aminoalkylsubstituted aromatic groups and/or the 2-hydroxypropane groups moleculargroups described above. For example, in addition to the aforementionedpreferred groups, some of the aminomethyl substitutions can be replacedwith oxy substitutions, (i.e., --O--Φ--O-- groups). These may beintroduced into the network by adducting the initial polyamine with thepolyglycidyl ethers of polyphenols (e.g., diglycidyl ether ofresorcinol) or by curing one of the preferred adducts with such apolyglycidyl ether of a polyphenol. Additionally, some of theaminomethyl substitutions can also be replaced with mixed substitutionssuch as --O--Φ--N< groups. These particular groups could be the residueof adducting or curing the initial polyamine with triglycidylpara-aminophenol.

Although not exhibiting performance properties which may becharacterized as preferred for the purposes of this invention, the curedpolymer network of the gas barrier coating can also include: --O--Φ--CH₂--Φ--O-- groups, which are the residues of novolac epoxy resins orbisphenol F epoxy resins; and --O--C(O)--Φ--C(O)--O groups, which arederived from diglycidyl esters of aromatic acids.

While maximizing the content of the aminoalkyl substituted aromaticgroups and/or the 2-hydroxypropane groups present in the cured gasbarrier coating composition is generally desirable, it has also beenfound to be additionally advantageous that the content of certainmolecular groups be minimized in, or even essentially absent from, thegas barrier's cured polymer network. For example, the groups that arepreferably avoided include unsubstituted alkyl chains, particularlyalkylene polyamine groups, as well as isopropylidene groups (i.e., as inbisphenol A).

It should be apparent from the description herein that the desiredmolecular groups may be introduced into the cured polymeric network ofthe gas barrier coating composition by the initial polyamine, thepolyamine adduct or the epoxide curing component (i.e., polyepoxide(B)). It should also be apparent that the various substitutions on thearomatic members described above may be provided in combination witheach other on the same molecule in the reactants.

The gas barrier coatings of the present invention are thermosetpolymers. This is desired feature for the packaging industry sincecontainers often rub together during processing and shipping. Since thegas barrier coatings of this invention are thermosetting polymers, anysuch rubbing together of adjacent containers will be less likely tocause localized softening of the barrier coatings when compared tothermoplastic gas barrier coatings.

The OPC value of the cured gas barrier coating compositions prepared inaccordance with this invention is not more than 0.05. If even lower OPCvalues are desired, the cured gas barrier coating composition of thisinvention can have OPC values of not more than 0.04, and even of notmore than 0.03.

When practicing this invention, the gas barrier coating composition canbe applied over a substrate as either a solvent-based or anaqueous-based thermosetting coating composition. If solvents are used,they should be chosen so as to be compatible with the substrate beingcoated, and also provide desirable flow properties to the liquidcomposition during application. Suitable solvents which can be usedinclude: oxygenated solvents, such as glycol ethers (e.g.,2-methoxyethanol, 2-ethoxyethanol, 2-propoxyethanol, 2-butoxyethanol,1-methoxy-2-propanol and the like); or alcohols such as methanol,ethanol, propanol and the like. Glycol ethers, such as 2-butoxyethanoland 1-methoxy-2-propanol, are more preferred with 1-methoxy-2-propanolbeing most preferred. The use of 1-methoxy-2-propanol is preferred forits rapid evaporation rate, which minimizes solvent retention in thecured film. In order to obtain desired flow characteristics in some ofthe embodiments using a pre-reacted adduct, use of 2-butoxyethanol maybe preferred. Moreover, in embodiments not requiring slow evaporatingsolvents for the sake of flow properties, the solvents listed here maybe diluted with less costly solvents such as toluene or xylene. Thesolvent may also be a halogenated hydrocarbon. For example, achlorinated hydrocarbon, such as methylene chloride,1,1,1-trichloroethane and the like (usually considered fast evaporatingsolvents), may be especially useful in obtaining cured barrier films.Mixtures of such solvents may also be employed. Non-halogenated solventsare preferred where the resultant barrier material is desired to behalide-free.

The resin may also be in an aqueous medium (i.e., the ungelledamine-functional polymeric resin may be an aqueous solution ordispersion). For example, when polyepoxide (B) is water-soluble (e.g.,the polyglycidyl ether of an aliphatic diol), the ungelledamine-functional polymeric resin can be utilized as an aqueous solution.Otherwise, with water-insoluble polyepoxides, the ungelledamine-functional polymeric resin can have sufficient amine groupsneutralized with an organic acid (e.g., formic acid, lactic acid oracetic acid), or with an inorganic acid (e.g., hydrochloric acid orphosphoric acid), to allow solubilization of the ungelledamine-functional polymeric resin in an aqueous medium. For suchaqueous-based systems, an organic acid is typically preferred.

Generally, for embodiments employing the pre-reacted adduct approach,the solution of the amine-functional polymeric coating ready forapplication will have a weight percent of resin solids in the range offrom about 15 weight percent to about 50 weight percent, and preferablyfrom about 25 weight percent to about 40 weight percent. Higher weightpercent solids may present application difficulties, particularly withspray application, while lower weight percentages will typically requireremoval of greater amounts of solvent during the curing stage. For theembodiments using direct reaction of the initial polyamine and theepoxide, solids contents above 50 weight percent can be appliedsuccessfully.

Gas barrier coating composition of the present invention can furtherinclude other additives known to those skilled in the art. Some of themore common additives which can be present include: pigments, silicones,surfactants, and/or catalysts for coating compositions which involve anepoxy-amine reaction. Each of these specific optional components will bediscussed below.

With regard to the use of pigments, in addition to imparting colorand/or tint to the gas barrier material, their use can also even furtherreduce the amount of gas that permeates there through. If employed, theweight ratio of pigment to binder is typically not more than about 1:1,preferably not more than about 0.3:1, and more preferably not more thanabout 0.1:1. The binder weight used in these ratios is the total solidsweight of the polyamine-polyepoxide resin in the gas barrier coatingcomposition.

With regard to the use of silicones, they may be included in the gasbarrier coating composition to assist in wetting the substrate overwhich the barrier material will be applied. Generally, silicones whichcan be used for this purpose include various organosiloxanes such aspolydimethylsiloxane, polymethylphenylsiloxane and the like. Specificexamples of such include: SF-1023 silicone (a polymethylphenylsiloxaneavailable from General Electric Co.), AF-70 silicone (apolydimethylsiloxane available from General Electric Co.), and DF-100 Ssilicone (a polydimethylsiloxane available from Mazer Chemicals, adivision of PPG Industries, Inc.). If employed, such silicones aretypically added to the gas barrier coating composition in amountsranging from about 0.01 to about 1.0 percent by weight based on totalresin solids in the gas barrier coating composition.

With regard to the use of surfactants, they are typically included inthe aqueous-based versions of the gas barrier coating composition.Examples of surfactants that can be used for this purpose include anysuitable nonionic or anionic surfactant. If employed, such surfactantsare typically present in an amount ranging from about 0.01 to about 1.0percent by weight based on the total weight of the gas barrier coatingcomposition.

With regard to the use of catalysts, they may be included in the gasbarrier coating composition to aid in the reaction between polyamine (A)and polyepoxide (B). Generally, any suitable catalyst that is used forepoxy-amine reactants can be employed when practicing this invention.Examples of such suitable catalysts include: dihydroxy aromatics (e.g.,resorcinol), triphenyl phosphite, calcium nitrate and the like.

Typically, when applying the gas barrier coating composition to asubstrate, the components of an gas barrier coating composition (i.e.,polyamine (A), polyepoxide (B) and filler (C)) are first thoroughlymixed together. After mixing, the gas barrier coating composition can beimmediately applied to the substrate, or held for a period of timetypically ranging from about 1 minutes to about 60 minutes prior toapplication to improve cure and/or clarity. This holding time can bereduced and/or eliminated when the initial polyamine is a pre-reactedadduct or when the solvent employed is 2-butoxyethanol.

When practicing this invention, the gas barrier coating composition canbe applied by any conventional means known to those skilled in the art(e.g., spraying, rolling, dipping, brushing and the like). Preferredmethods of application include spray and/or dipping processes.

After application of the gas barrier coating composition, it may becured at temperatures as low as ambient temperature by allowing for agradual cure over several hours to several days. However, such lowtemperature curing is generally slower than desired for commercialproduction lines. It is also not an efficient means of removing solventfrom the cured barrier material. Therefore, in one preferred embodiment,the oxygen barrier material is cured by heating it at elevatedtemperatures as high as possible without distorting the substrate overwhich it is applied.

For a relatively "slow" solvent (i.e., a solvent having a relatively lowevaporation rate), curing temperatures typically range from about 55° C.to about 110° C., and preferably from about 70° C. to about 95° C. Atsuch curing temperatures, curing times will typically range from about 1minute to about 60 minutes.

For a relatively "fast" solvent (i.e., a solvent having relatively highevaporation rate), curing temperatures typically range from about 35° C.to about 70° C., and preferably from about 45° C. to about 65° C. Atsuch curing temperatures, curing times will typically range from about0.5 minute to about 30 minutes.

The cured gas barrier coatings of the present invention can have anysuitable dry film thickness. Although thicker coatings typically providegreater gas protection, the packaging industry typically prefers thinnercoating for economic reasons. As such, the cured gas barrier coatings ofthis invention generally have a dry film thickness of not more thanabout 1.0 mil (25.4 microns). If even thinner films are desired, thecured gas barrier coating of the present invention can have a dry filmthickness of not more than about 0.5 mil (12.7 microns), and even of notmore than about 0.3 mil (7.6 microns).

In addition to having OPC values of not more than 0.05, the cured gasbarrier coatings of this invention are also relatively smooth,transparent and glossy. Specifically, the cured gas barrier coatingsprepared in accordance with this invention have a 20° gloss of at least60% reflected light. Preferably, the cured gas barrier coatings have a20° gloss of at least 70% reflected light, and more preferably of atleast 80% reflected light.

The gas barrier coating composition may be applied over a substrate as asingle layer or as multiple layers with multiple heating stages toremove solvent from each subsequent layer. Both are referred to hereinas "multilayer" packaging materials.

The present invention also provides a multilayer packaging materialwhich has improved gas barrier properties. The multilayer packagingmaterial of the present invention includes at least one layer of asubstrate material and at least one layer of a gas barrier materialwhich is the filler-containing, cured reaction product of polyamine (A)and polyepoxide (B) as described above.

When making a multilayer packaging material in accordance with thisinvention, the gas barrier coating composition of the present inventioncan be applied over any suitable substrate. Typically, however, it isapplied over a gas-permeable substrate, and more typically, it isapplied over a polymeric, gas-permeable packaging material.

Gas-permeable materials over which the gas barrier coating compositioncan be applied typically include any suitable polymeric material throughwhich gases can pass and which can be used as a packaging material.Examples of such suitable gas-permeable materials which can be used inthe packaging of food, beverages, chemicals, medicines, medicalsupplies, and the like include: polyesters, polyolefins, polyamides,cellulosics, polystyrenes, and polyacrylics, and the like. Due to theirphysical properties, the preferred polymeric packaging materials for usein making food and beverage containers for such types ofoxygen-sensitive products typically include a polyester. Examples ofpolyesters which can be used for this purpose include: PET,poly(ethylene napthalate) ("PEN"), and/or combinations thereof.

In one embodiment of a multilayer packaging material encompassed by thepresent invention, a laminate is formed which includes a layer of thegas barrier material. Here, the gas barrier material is applied onto afirst layer of a suitable substrate material. Thereafter, a second layerof a similar or dissimilar substrate material is applied over the layerof the gas barrier material to form a laminate.

In embodiments of the present invention wherein a polyolefin (e.g.,polypropylene) is the gas-permeable packaging material, the surface ofthe polyolefin is preferably treated to increase surface tension andpromote better adhesion of the oxygen barrier material to the polyolefinmaterial. Examples of treating techniques which can be used for thispurpose include: flame-treating, corona-treating and the like.

Specific examples of such treating techniques are described in detail byPinner et al. in Plastics: Surface and Finish, Butterworth & Co. Ltd.(1971), Chapter 3. The description of the surface treatments describedin Pinner et al is herein incorporated by reference.

In another embodiment of a multilayer packaging material encompassed bythe present invention, a sheet or film stock, which is subsequentlyformed into containers by conventional plastic processing techniques, iscoated with the gas barrier coating composition disclosed herein.Thereafter, the coated film or sheet is formed into articles such as:wrappers, bags, containers and the like.

In still another embodiment of a multilayer packaging materialencompassed by the present invention, pre-formed containers (e.g., maltbeverage bottles), are coated with at least one layer of the gas barriercoating composition disclosed herein.

The multilayer packaging materials of the present invention are ideallysuited for packaging of food, beverages, chemicals, medicines, medicalsupplies, and the like. Their very low OPC values make them especiallysuited for packaging malt beverages such as beer and ale.

Specifically, the malt beverage industry has established very strictquality standards for small beverage containers (e.g., 12 ounce (355milliliter) bottles made out of PET having an average wall thickness of15 mils (381 microns)). Specifically, according to this shelf-lifestandard typically, not more than 5 ppm of oxygen should pass throughthe walls of the sealed container over a 90-day storage period atambient temperatures and 50% R.H. Parts per million of oxygen is basedupon the weight of oxygen to the weight of the beverage (1 cubiccentimeter of oxygen weighs 0.0014 gram). For example, one cubiccentimeter of oxygen in 12 ounces of beverage would be 4.0 ppm ((0.0014grams per cubic centimeter of oxygen/355 cubic centimeters in a 12 ouncebottle)×10⁶). Preferred levels of performance for the malt beverageindustry would entail that, over the 90-day storage period at ambienttemperatures and 50% R.H., not more than 4 ppm oxygen, more preferablynot more than 3 ppm oxygen, and even more preferably not more than 2 ppmof oxygen pass through the walls of the sealed container. In order tomeet these desired objectives, the cured gas barrier coating layer of amultilayer packaging material should have an OPC value of not more than0.05, preferably, not more than 0.04, more preferably not more than0.03, and even more preferably not more than 0.02. As stated above anddemonstrated in the examples which follow, the gas barrier coatings ofthis invention meet these strict standards.

As used herein, desired OPC values are calculated by Equation (A):

    t=O.sub.i (3a).sup.-1 (L.sub.1 /P.sub.1 +L.sub.2 /P.sub.2 +. . . +L.sub.n /P.sub.n)                                                 (A)

where:

t=desired storage time in days;

O_(i) =desired maximum level of oxygen ingress through the walls of asealed multilayer container, in ppm;

a=ratio of exterior surface area of the multilayer container, in squareinches, to internal volume ratio of the container, in cubic centimeters;

L=average thickness of each layer of the multilayer container, in mils;and

P=OPC value of each individual layer of the multilayer container.

For example, if a 0.3 mil (7.6 micron) thick gas barrier coating is tobe coated over a typical 12 ounce (355 milliliter) beverage bottle madeout of PET, and if it is desired that not more than 5 ppm of oxygenpermeate through the walls of the sealed, coated bottle after 90 days ofstorage at 30° C. and 50% R.H., the necessary minimum OPC value of thegas barrier coating to achieve this desired result can be calculated byusing Equation A. Specifically, in this example, a typical 12 ounce (355milliliter) beverage bottle made out of PET has an internal volume of355 cubic centimeters, a surface area of 49 square inches (35.6 squarecentimeters) and an average wall thickness of 15 mils (381 microns).Moreover, uncoated PET has an OPC value of 6.0. When plugging this datainto Equation A: t is 90 days; O_(i) is 5 ppm; a is 49 square inches/355cubic centimeters; L₁ is 15 mils; L₂ is 0.3 mil; and P₁ is 6.0.Accordingly, solving Equation A for P₂ (i.e., the OPC value for the gasbarrier coating needed to achieve the desired result at 30° C. and 50%R.H.) yields 0.06.

It has been observed that OPC values of gas barrier coatings made inaccordance with this invention can be even further improved by treatingthem with carbon dioxide (CO₂). If it is desired to even further lowerthe OPC value of the gas barrier coatings of this invention, this can beachieved by treating them with CO₂. The CO₂ treatment, if used,typically occurs after the coatings have been applied over a substrate.The extent of CO₂ treatment necessary for the gas barrier coating toobtain the desired OPC value depends upon the duration, temperature andCO₂ pressure during the CO₂ treatment process.

In one embodiment of treating a gas barrier coating of this inventionwith CO₂, the gas barrier coating is applied over a packaging material.Thereafter, the coating is exposed to a CO₂ atmosphere at an elevatedpressure and temperature. During such a treatment process, CO₂ pressurestypically range from about 30 to about 1,000 pounds per square inch(about 2 bar to about 70 bar); treatment temperatures typically rangefrom about 32° F. (0° C.) to about 200° F. (93° C.); and treatmentduration typically ranges from about 1 minute to about 6 weeks.Preferably, during the treatment process CO₂ pressures range from about30 to about 100 pounds per square inch (about 2 bar to about 7 bar);treatment temperatures range from about 40° F. (14° C.) to about 150° F.(65° C.); and treatment duration is typically range from about 1 hour toabout 3 weeks.

In another embodiment of treating a gas barrier coating of thisinvention with CO₂, the gas barrier coating is applied over agas-permeable packaging material in the form of a sealable container.Thereafter, the container is at least partially filled with a carbonatedbeverage and sealed. Since the packaging material is gas-permeable, CO₂can pass there through. As such, the carbonated beverage is being usedas the CO₂ treating medium. In this embodiment of treating a gas barriercoating of this invention with CO₂, the gas-permeable material shouldhave an OPC value greater than about 0.5.

The multilayer packaging materials of the present invention are ideallysuited for packaging of food, beverages, chemicals, medicines, medicalsupplies, and the like. However, their very low OPC values makes themespecially suited for packaging malt beverages.

It is known that malt beverages are not stable in light with wavelengthsof electromagnetic radiation ranging from 300 nanometers (nm) to 500 nm(hereinafter referred to as "product damaging light"). It is also knownthat brown or dark amber-tinted glass substantially blocks most of thisproduct damaging light. As used herein, the term "substantially blocks"means that less than about 10%, preferably less than about 7%, morepreferably less than about 5% and even more preferably less than about3% of this product damaging light passes therethrough. Accordingly, ifthe multilayer packaging materials of the present invention are used forpackaging malt beverages, the gas barrier coating and/or thegas-permeable substrate should be tinted so as to substantially blockthe transmission of this product damaging light.

If the gas-permeable material is tinted so as to substantially blockproduct damaging light, this can be done by any suitable means known tothose in the art. However, from a recycling standpoint, it isundesirable to recycle tinted plastics since this often requires manualsorting. It would greatly reduce recycling time and costs if all of theplastic being recycled was clear and un-tinted. Accordingly, since thegas barrier coating of this invention are easily removable by arecycler, the use of a tinted gas barrier coating over an un-tintedgas-permeable polymeric material is preferred.

When tinting the gas barrier coating so as to substantially block theaforementioned product damaging light, the weight ratio of pigment tobinder is typically not more than about 1:1, preferably not more thanabout 0.3:1, and more preferably not more than about 0.1:1. The binderweight used in these ratios is the total solids weight of thepolyamine-polyepoxide resin in the gas barrier coating.

The pigments typically used in tinting gas barrier coatings for use inmultilayer packaging materials for the malt beverage industry can be anysuitable particulate pigment and/or dye which has the followingproperties: it substantially blocks the aforementioned product damaginglight; it results in a glossy, transparent gas barrier coating; and itdoes not significantly adversely affect the gas barrier properties ofthe resulting gas barrier coating. Examples of dyes which can be usedfor this purpose include brown dyes, amber dyes and/or a blend of redand yellow dyes. Examples of pigments which can be used for this purposeinclude brown pigments, amber pigments and/or a blend of red and yellowpigments. Preferably, pigments are used since they typically improve theOPC value of the resulting tinted coating. A preferred pigment is ironoxide since it imparts a dark amber color which closely matches thecolor of most conventional glass beer bottles.

EXAMPLES

The present invention is more particularly described in the followingexamples which are intended as illustration only and are not intended tolimit the scope thereof. Unless otherwise indicated, all weightpercentages are based upon the total weight of the resin solids of thegas barrier coating composition. Filler equivalent particle sizemeasurements set out in TABLE 1 were performed with a HORIBA LA-900laser scattering particle size distribution analyzer.

SAMPLE PREPARATION FOR DETERMINING PARTICLE SIZE DISTRIBUTION

The preparation of samples for determining particle size distribution bythe HORIBA LA-900 laser scattering particle size distribution analyzerwas as follows: 1 to 2 grams of the particular platelet-type filler wasadded to a beaker containing 10 to 15 milliliters of 1-methoxy-2propanol which was used as the dispersing agent for all samples. Thismixture was then stirred vigorously for approximately 1 minute to form adispersion. Thereafter, the beaker containing the dispersion was placedin an ultrasonic bath for approximately 1 minute to disperse any airtrapped between the particles and dispersing agent.

The HORIBA LA-900 laser scattering particle size distribution analyzerwas then calibrated by filling a fraction cell supplied with theapparatus with 1-methoxy-2 propanol, placing the filled fraction cell inthe appropriate analyzing chamber of the HORIBA LA-900 laser scatteringparticle size distribution analyzer, and analyzing the sample.Thereafter, an identical fraction cell used to calibrate the machine wasfilled with a sample of the dispersion containing the platelet-typefiller. The fraction cell was then placed in the appropriate analyzingchamber of the HORIBA LA-900 laser scattering particle size distributionanalyzer and analyzed. The analyzing chamber is equipped with anultrasonic bath which is designed the keep the dispersed particles inmotion during their analysis. The results of this analysis are set outin TABLE 1.

                                      TABLE 1                                     __________________________________________________________________________              Example in                                                                          No. Mean                                                                           Vol. Mean                                                                          Number Percent                                                                        Number Percent                              Platelet- Which Particle                                                                           Particle                                                                           of Particles                                                                          of Particles                                Type      Filler Was                                                                          Diameter                                                                           Diameter                                                                           Greater Than 7                                                                        Greater Than 30                             Filler    Used  (Microns)                                                                          (Microns)                                                                          Microns Microns                                     __________________________________________________________________________    Magna Pearl 2000.sup.1                                                                  I/II  9.3  13.3 92      0.5                                         Mica M RP.sup.2                                                                         III/IV                                                                              9.8  14.6 95      1.5                                         Mearl Mica SVA.sup.3                                                                    V/VI  10.7 16.8 98      4.0                                         EM Fine Mica.sup.2                                                                      VII/VIII                                                                            11.6 18.7 98      2.5                                         Afflair 110.sup.4                                                                       IX/X  6.1  8.5  65      0                                           Magna Pearl 3000.sup.1                                                                  XI/XII                                                                              5.8  8.0  55      0                                           Miro-Mica C-4000.sup.5                                                                  XIII/XIV                                                                            11.2 27.6 98      35                                          WG 325.sup.5                                                                            XV/XVI                                                                              9.8  68.2 90      22                                          ASP-NC.sup.6                                                                            XVII/XVIII                                                                          3.4  7.8  50      0                                           Micro Talc MP12-52.sup.7                                                                XIX/XX                                                                              3.7  7.3  65      0.5                                         __________________________________________________________________________     .sup.1 White pearlescent muscovite mica coated with TiO.sub.2 available       from Mearl Corp.                                                              .sup.2 Gray powder muscovite mica filler from EM Industries, Inc.             .sup.3 White waterground muscovite mica treated with lauroyl lysine           available from Mearl Corp.                                                    .sup.4 White pearlescent muscovite mica coated with TiO.sub.2 available       from EM Industries, Inc.                                                      .sup.5 Muscovite mica filler available from KMG Minerals, Inc.                .sup.6 Aluminum silica clay available from Engelhard Corp.                    .sup.7 Platy Montana talc available from Pfizer Minerals, Pigments &          Metals.                                                                  

EXAMPLES I-XXI

Examples I through XX are gas barrier coating compositions containingfillers, and Example XXI is a gas barrier coating composition which doesnot contain a filler. Examples I through XII demonstrate gas barriercoating compositions encompassed by this invention, while Examples XIIthrough XXI are provided for comparison. A comparison of Examples Ithrough XII with Examples XIII through XXI demonstrates the importanceof selecting a platelet-type filler having particle size distributionwithin the scope of the present invention.

For each of Examples I-XX, filler pastes were prepared by slowly siftingand blending 34.0 weight percent of one of the dry fillers set out inTABLE 1 into a liquid resin mixture consisting of: 33.0 weight percentof GASKAMINE® 328S (the reaction product of MXDA and epichlorohydrinwith any excess MXDA stripped therefrom, commercially available fromMitsubishi Gas Chemical Co.), and 33.0 weight percent of1-methoxy-2-propanol (commercially available from Dow Chemical Co. asDOWANOL® PM solvent). Each of the blends were then subjected to highspeed Cowles mixing until a smooth, uniform paste was formed (i.e., 15to 30 minutes).

Filler-containing gas barrier coatings were then prepared containing 10%filler and 20% filler for each of the fillers in TABLE 1 using thefiller pastes made above. These percentages are based upon the totalsolids weight of all the ingredients in the filler-containing gasbarrier coating.

The filler-containing gas barrier coatings containing 10% filler wereprepared by blending together the following ingredients: 11.6 weightpercent of GASKAMINE® 328S, 8.4 weight percent of N,N,N',N'-tetrakis(oxiranylmethyl)-1,3-benzene dimethanamine (commercially available fromMitsubishi Gas Chemical Co. as TETRAD-X epoxy resin), 68.1 weight ofDOWANOL® PM solvent, 7.3 weight percent of the filler paste preparedabove, 4.5 weight percent of ethyl acetate, and 0.1 weight percent ofSF-1023 silicone (a polymethylphenylsiloxane commercially from GeneralElectric Co.).

The filler-containing gas barrier coatings containing 20% filler wereprepared by blending together the following ingredients: 7.7 weightpercent of GASKAMINE® 328S, 7.5 weight percent of TETRAD-X epoxy resin,66.3 weight of DOWANOL® PM solvent, 14.4 weight percent of theappropriate filler paste prepared above, 4.0 weight percent of ethylacetate, and 0.1 weight percent of SF-1023 silicone.

For Example XXI, a barrier coating composition which did not contain anyfiller was prepared by blending together the following ingredients: 17.7weight percent GASKAMINE® 328S, 10.6 weight percent of TETRAD-X epoxyresin, 64.7 weight percent of DOWANOL® PM solvent, 5.7 weight percent ofethyl acetate, 1.2 weight percent of deionized water, and 0.1 weightpercent of SF-1023 silicone.

All of the resulting gas barrier coating compositions were allowed tostand for about 15 minutes prior to use. Thereafter, each coatingcomposition was spray applied to samples of a 2-mil thick PET film andbaked for about 30 minutes at 145° F. (63° C.) to produce a dry coatinghaving a thickness ranging from of 0.3 to 0.5 mil. All of the coatedfilms were allowed to age for four days at 70° F. (21° C.) and 50% R.H.prior to testing.

TESTING OF COATING SAMPLES

Oxygen transmission rates were measured using an OXTRAN 20/20 at 30° C.and 50-55% R.H. and at 30° C. and 70-75% R.H.. OPC values of the gasbarrier layer for each of the coated samples were then calculated byusing the following equation:

    1/R.sub.1 =1/R.sub.2 +DFT/PO.sub.2

where:

R₁ =coated PET transmission rate in cc/100 in² /atmosphere/day;

R₂ =PET film transmission rate in cc/100 in² /atmosphere/day;

DFT=coating dry film thickness in mils; and

PO₂ =OPC value of coating in cc-mil/100 in² /atmosphere/day.

The gloss of each of the coating samples was measured at an angle of 20°using a Gardner Glossgard IIa 20° Glossmeter from Gardner Instruments.Roughness and clarity of the coating was determined by a visual ratingon a scale of 0 to 10, with 0 being very smooth and clear and 10 beingextremely rough and hazy. The results of these tests are set out inTABLE 2.

                                      TABLE 2                                     __________________________________________________________________________                                    Oxygen Permeability Constant of                                               the Gas Barrier Material Layer                     Filler       Roughness                                                                          20° Gloss                                                                       at 50-55%                                                                            at 70-75%                              Example                                                                            (Wt. % - Type)                                                                             Index                                                                              (% Reflected Light)                                                                    R.H.   R.H.                                   __________________________________________________________________________    I    10% - Magna Pearl 2000                                                                     0    94       0.061  0.11                                   II   20% - Magna Pearl 2000                                                                     0    74       0.025  0.05                                   III  10% - Mica M RP                                                                            0    84       0.049  0.22                                   IV   20% - Mica M RP                                                                            0    83       0.017  0.11                                   V    10% - Mearl Mica SVA                                                                       1    83       0.044  0.16                                   VI   20% - Mearl Mica SVA                                                                       2    91       0.030  0.09                                   VII  10% - EM Fine Mica                                                                         1    87       0.042  0.19                                   VIII 20% - EM Fine Mica                                                                         2    63       0.033  0.07                                   IX   10% - Afflair 110                                                                          1    74       0.039  0.11                                   X    20% - Afflair 110                                                                          1    66       0.029  0.08                                   XI   10% - Magna Pearl 3000                                                                     0    98       0.085  0.17                                   XII  20% - Magna Pearl 3000                                                                     0    94       0.045  0.1                                    XIII 10% - C-4000 5    34       0.043  0.12                                   XIV  20% - C-4000 8    2        0.038  0.08                                   XV   10% - WG 325 10   5        0.052  0.19                                   XVI  20% - WG 325 10   1        0.037  0.09                                   XVII 10% - ASP-NC 2    78       0.052  0.13                                   XVIII                                                                              20% - ASP-NC 4    53       0.038  0.09                                   XIX  10% - Micro Talc MP-12-52                                                                  4    53       0.063  0.14                                   XX   20% - Micro Talc MP-12-52                                                                  5    23       0.076  0.16                                   XXI  None         0    100      0.085  0.27                                   __________________________________________________________________________

As can be seen from the data in TABLE 2, the filler-containing gasbarrier coatings of Examples XII-XVI and XVIII-XX were rough and hazy(i.e., each had a roughness index of greater than 4) and had a 20° glossof less than 60 percent reflected light. Moreover, the filler-containinggas barrier coatings of Examples XVII, XIX-XXI each had an OPC value, at50%-55% R.H. and 30° C., of greater than 0.05. Accordingly, the use ofplatelet-type fillers having a particle size distribution of those usedin Examples XIII through XX did not result in a gas barrier coatingwhich had a 20° gloss of at least 60 percent reflected light as well asan OPC value, at 50%-55% R.H. and 30° C., of not more than 0.05.

Although the fillers used in Examples I and XI had a particle sizedistribution that resulted in gas barrier coatings which had an OPCvalue, at 50%-55% R.H. and 30° C., of greater than 0.05, this onlyoccurred when the amount of filler employed was 10 weight percent.However, when these fillers were present in an amount greater than 10weight percent (e.g., Examples II and XII), they had an OPC value, at50%-55% R.H. and 30° C., of not more than 0.05. Accordingly, the use ofplatelet-type fillers having a particle size distribution as thoseemployed in Examples I/II and XI/XII (e.g., those which have a numbermean particle diameter in the range from about 5.5 to less than 9.5microns, and/or a volume mean particle diameter in the range from about8 to less than 14 microns), are within the scope of this invention whenpresent in an amount of greater than 10 weight percent.

The fillers used in Examples III and X had a particle size distributionwhich resulted in gas barrier coatings which had an OPC value, at50%-55% R.H. and 30° C., of greater than 0.050 and a 20° gloss of atleast 60% reflected light. Accordingly, the use of platelet-type fillershaving a particle size distribution as those employed in Examples IIIthorough X is within the scope of the present invention regardless ofwhether they were present in an amount of 10 or 20 weight percent.

It is evident from the foregoing that various modifications, which areapparent to those skilled in the art, can be made to the embodiments ofthis invention without departing from the spirit or scope thereof.Having thus described the invention, it is claimed as follows.

We claim:
 1. A gas barrier coating composition comprising:(a) polyamine(A) comprising at least one of the following:(i) a first polyamine, and(ii) an ungelled amine-epoxide adduct which is the reaction product ofthe first polyamine and at least one of the following:a.epichlorohydrin, and b. a polyepoxide having at least two glycidylgroups linked to an aromatic member; (b) polyepoxide (B) comprising apolyepoxide having at least two glycidyl groups linked to an aromaticmember; and (c) filler (C) comprising a platelet shaped inorganic fillerwith the following particle size distribution:(i) a number mean particlediameter in the range from about 5.5 to about 15 microns, and (ii) avolume mean particle diameter in the range from about 8 to about 25microns.
 2. A gas barrier coating composition as in claim 1 whereinfiller (C) has the following particle size distribution: (a) a numbermean particle diameter ranging from about 9.5 to about 15 microns, and(b) a volume mean particle diameter ranging from about 14 to about 25microns.
 3. A gas barrier coating composition as in claim 2 whereinfiller (C) is present in an amount ranging from about 5 to about 50weight percent, based upon the total solids weight of the gas barriercoating composition.
 4. A gas barrier coating composition as in claim 1wherein said platelet shaped inorganic filler comprises at least one ofthe following: mica, clay, talc, micaeous iron oxide, silica, flakedmetals, flaked graphite, flaked glass or flaked phthalocyanine.
 5. A gasbarrier coating composition as in claim 1 wherein said platelet shapedinorganic filler comprises mica.
 6. A gas barrier coating composition asin claim 1 wherein at least 50 percent of the carbon atoms in the firstpolyamine are in one or more aromatic rings.
 7. A gas barrier coatingcomposition as in claim 1 wherein the first polyamine is represented bythe structure:

    Φ-(R.sup.1 NH.sub.2).sub.k

where:k is 1.5 or greater, Φ is an aromatic-containing compound, and R¹is an alkyl group having between 1 and 4 carbon atoms.
 8. A gas barriercoating composition as in claim 7 wherein k is 1.9 or greater and R¹ isan alkyl group which is not greater than C₂.
 9. A gas barrier coatingcomposition as in claim 1 wherein about 10 to about 80 percent of theungelled amine-epoxide adduct's active amine hydrogens are reacted withepoxy groups prior to reacting the ungelled amine-epoxide adduct withpolyepoxide (B).
 10. A gas barrier coating composition as in claim 1wherein polyamine (A) comprises an ungelled amine-epoxide adduct whichis the reaction product of the first polyamine and epichlorohydrin. 11.A gas barrier coating composition as in claim 1 wherein polyamine (A)comprises an ungelled amine-epoxide adduct which is the reaction productof the first polyamine and a polyepoxide having at least two glycidylgroups linked to an aromatic member.
 12. A gas barrier coatingcomposition as in claim 11 wherein the polyepoxide having at least twoglycidyl groups linked to an aromatic member, which reacts with thefirst polyamine to form the ungelled amine-epoxide adduct, isrepresented by the structure: ##STR2## where: R² is phenylene ornaphthylene;X is N, NR³ ', CH₂ N, CH₂ NR³, O, and/or C(O)--O, where R³is an alkyl group containing 1 to 4 carbon atoms, a cyanoethyl group orcyanopropyl group; n is 1 or 2; and m is 2 to
 4. 13. A gas barriercoating composition as in claim 12 wherein the polyepoxide having atleast two glycidyl groups linked to an aromatic member, which reactswith the first polyamine to form the ungelled amine-epoxide adduct,comprises at least one of the following: N,N,N',N'-tetrakis(oxiranylmethyl)-1,3-benzene dimethanamine, resorcinol diglycidyl ether,diglycidyl esters of phthalic acid or triglycidyl para-aminophenol. 14.A gas barrier coating composition as in claim 12 wherein the firstpolyamine, which reacts to form the ungelled amine-epoxide adduct,comprises m-xylylenediamine.
 15. A gas barrier coating composition as inclaim 1 wherein polyepoxide (B) is represented by the structure:##STR3## where: R² is phenylene or naphthylene;X is N, NR³ ', CH₂ N, CH₂NR³, O, and/or C(O)--O, where R³ is an alkyl group containing 1 to 4carbon atoms, a cyanoethyl group or cyanopropyl group; n is 1 or 2; andm is 2 to
 4. 16. A gas barrier coating composition as in claim 15wherein polyepoxide (B) comprises at least one of the following:N,N,N',N'-tetrakis (oxiranylmethyl)-1,3-benzene dimethanamine,resorcinol diglycidyl ether, diglycidyl esters of phthalic acid ortriglycidyl para-aminophenol.
 17. A gas barrier coating composition asin claim 1 wherein filler (C) has at least one of the following particlesize distribution parameters: (a) a number mean particle diameter in therange from about 5.5 to less than 9.5 microns, or (b) a volume meanparticle diameter in the range from about 8 to less than 14 microns. 18.A gas barrier coating composition as in claim 17 wherein filler (C) ispresent in an amount ranging from about 12 to about 50 weight percent,based upon the total solids weight of the gas barrier coatingcomposition.
 19. A gas barrier coating composition as in claim 17wherein said platelet shaped inorganic filler comprises at least one ofthe following: mica, clay, talc, micaeous iron oxide, silica, flakedmetals, flaked graphite, flaked glass or flaked phthalocyanine.
 20. Agas barrier coating composition as in claim 17 wherein said plateletshaped inorganic filler comprises mica.
 21. A gas barrier coatingcomposition as in claim 17 wherein polyamine (A) comprises an ungelledamine-epoxide adduct.
 22. A multilayer packaging material having atleast one gas-permeable packaging material layer and at least one gasbarrier material layer, wherein said gas barrier material layercomprises:(a) the reaction product of polyamine (A) and polyepoxide (B),wherein polyamine (A) comprises at least one of the following:(i) afirst polyamine, and (ii) an ungelled amine-epoxide adduct which is thereaction product of the first polyamine and at least one of thefollowing:a. epichlorohydrin, and b. a polyepoxide having at least twoglycidyl groups linked to an aromatic member through an interveninggroup; and (b) filler (C) which comprises a platelet shaped inorganicfiller with the following particle size distribution:(i) a number meanparticle diameter in the range from about 5.5 to about 15 microns, and(ii) a volume mean particle diameter in the range from about 8 to about25 microns.
 23. A multilayer packaging material as in claim 22 whereinfiller (C) has the following particle size distribution: (a) a numbermean particle diameter ranging from about 9.5 to about 15 microns, and(b) a volume mean particle diameter ranging from about 14 to about 25microns.
 24. A multilayer packaging material as in claim 23 whereinfiller (C) is present in the gas barrier material layer in an amountranging from about 5 to about 50 weight percent, based upon the totalsolids weight of the gas barrier material layer.
 25. A multilayerpackaging material as in claim 22 wherein said platelet shaped inorganicfiller comprises at least one of the following: mica, clay, talc,micaeous iron oxide, silica, flaked metals, flaked graphite, flakedglass or flaked phthalocyanine.
 26. A multilayer packaging material asin claim 22 wherein said platelet shaped inorganic filler comprisesmica.
 27. A multilayer packaging material as in claim 22 wherein atleast 50 percent of the carbon atoms in the first polyamine are in oneor more aromatic rings.
 28. A multilayer packaging material as in claim22 wherein 1 wherein the first polyamine is represented by thestructure:

    Φ-(R.sup.1 NH.sub.2).sub.k

where:k is 1.5 or greater, Φ is an aromatic-containing compound, and R¹is an alkyl group having between 1 and 4 carbon atoms.
 29. A multilayerpackaging material as in claim 27 wherein k is 1.9 or greater and R¹ isan alkyl group which is not greater than C₂.
 30. A multilayer packagingmaterial as in claim 22 wherein about 10 to about 80 percent of theungelled amine-epoxide adduct's active amine hydrogens are reacted withepoxy groups prior to reacting the ungelled amine-epoxide adduct withpolyepoxide (B).
 31. A multilayer packaging material as in claim 22wherein polyamine (A) comprises an ungelled amine-epoxide adduct whichis the reaction product of the first polyamine and epichlorohydrin. 32.A multilayer packaging material as in claim 22 wherein polyamine (A)comprises an ungelled amine-epoxide adduct which is the reaction productof the first polyamine and the polyepoxide having at least two glycidylgroups linked to an aromatic member.
 33. A multilayer packaging materialas in claim 32 wherein the polyepoxide having at least two glycidylgroups linked to an aromatic member, which reacts with the firstpolyamine to form the ungelled amine-epoxide adduct, is represented bythe structure: ##STR4## where: R² is phenylene or naphthylene;X is N,NR³ ', CH₂ N, CH₂ NR³, O, and/or C(O)--O, where R³ is an alkyl groupcontaining 1 to 4 carbon atoms, a cyanoethyl group or cyanopropyl group;n is 1 or 2; and m is2to4.
 34. A multilayer packaging material as inclaim 33 wherein the polyepoxide having at least two glycidyl groupslinked to an aromatic member comprises at least one of the following:N,N,N',N'-tetrakis (oxiranylmethyl)-1,3-benzene dimethanamine,resorcinol diglycidyl ether, diglycidyl esters of phthalic acid ortriglycidyl para-aminophenol.
 35. A multilayer packaging material as inclaim 33 wherein the first polyamine comprises m-xylylenediamine.
 36. Amultilayer packaging material as in claim 22 wherein polyepoxide (B) isrepresented by the structure: ##STR5## where: R² is phenylene ornaphthylene;X is N, NR³ ', CH₂ N, CH₂ NR³, O and/or C(O)--O, where R³ isan alkyl group containing 1 to 4 carbon atoms, a cyanoethyl group orcyanopropyl group; n is 1 or 2; and m is 2 to
 4. 37. A multilayerpackaging material as in claim 36 wherein polyepoxide (B) comprises atleast one of the following: N,N,N',N'-tetrakis(oxiranylmethyl)-1,3-benzene dimethanamine, resorcinol diglycidyl ether,diglycidyl esters of phthalic acid or triglycidyl para-aminophenol. 38.A multilayer packaging material as in claim 21 wherein filler (C) has atleast one of the following particle size distribution parameters: (a) anumber mean particle diameter in the range from about 5.5 to less than9.5 microns, or (b) a volume mean particle diameter in the range fromabout 8 to less than 14 microns.
 39. A multilayer packaging material asin claim 38 wherein filler (C) is present in an amount ranging fromabout 12 to about 50 weight percent, based upon the total solids weightof the gas barrier coating composition.
 40. A multilayer packagingmaterial as in claim 38 wherein said platelet shaped inorganic fillercomprises at least one of the following: mica, clay, talc, micaeous ironoxide, silica, flaked metals, flaked graphite, flaked glass and flakedphthalocyanine.
 41. A multilayer packaging material as in claim 38wherein said platelet shaped inorganic filler comprises mica.
 42. Amultilayer packaging material as in claim 38 wherein polyamine (A)comprises an ungelled amine-epoxide adduct.
 43. A multilayer packagingmaterial as in claim 22 wherein the gas barrier material layer has anOPC value of not more than 0.05 when measured at about 30° C. and about50% relative humidity and a gloss, measured at an angle of 20°, of atleast 60% reflected light.
 44. A multilayer packaging material as inclaim 22 wherein said gas permeable packaging material comprises atleast one of the following: polyester, polyolefin, polyamide,cellulosic, polystyrene, or polyacrylic.
 45. A multilayer packagingmaterial as in claim 22 wherein the gas-permeable packaging materiallayer comprises a polyester.
 46. A multilayer packaging material as inclaim 22 wherein the gas-permeable packaging material comprises at leastone of the following: poly(ethylene terephthalate) or poly(ethylenenapthalate).
 47. A multilayer packaging material as in claim 22 whereinthe gas-permeable packaging material is a sealable container.
 48. Amultilayer packaging material as in claim 22 wherein the gas-permeablepackaging material is a malt beverage container.